Chapter 45.2 The Skeletal System. The Human Skeleton Has approximately 206 bones! Functions: Gives Shape and Support Protection Moves Muscles Forms Blood.

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The Skeletal System

Chapter 45.2The Skeletal System

The Human SkeletonHas approximately 206 bones!Functions:Gives Shape and SupportProtectionMoves MusclesForms Blood CellsStores Minerals- Ex: Calcium and PhosphorusBones are moist, living tissues (not dry!)

Parts of the Skeleton2 Parts:Axial- bones of the:SkullRibsSpineSternumAppendicular- bones of the:ArmsLegsScapulaClaviclePelvis

Bone StructurePeriosteum-tough membrane that surrounds the bones surface. Contains blood vessels to supply nutrients.Compact Bone- hard material found under the periosteum. Makes bones strong and capable of enduring large amounts of stress

Spongy Bone- network of connective tissue found under the compact bone. Hard/strong tissue. Makes bones lightMarrow: soft tissue in spongy boneRed: produces red blood cells, platelets, and white blood cellsYellow: consists mostly of fat cells and serves as an energy storage

Bone StructureCompact bone is composed of cylinders of mineral crystals and protein fibers called lamellaeIn the center of each cylinder is a narrow channel called a Haversian canalBlood vessels run through interconnected Haversian canals, which carries nutrients throughout the boneSurrounding each Haversian canal are protein fibers and ostecytes (bone cells)

Bone DevelopmentBones develop from cartilageConnective tissueTough, yet flexibleIn fetal development:Month 2: most of the skeleton is cartilageMonth 3: Ossification turns most cartilage into bonesSome cartilage is left for flexible areas between bonesEx: tip of the nose, outer ear, and inside the tracheaNormal bone development depends on regular exercise and diet, mainly calcium and vitamin D intakeLack of this can lead to osteoporosis

JointsThe place where 2 bones meetTough bands of connective tissue called ligaments hold the bones of the joint in placeSynovial fluid- a lubricating substance that helps protect the ends of the bones from damage by friction

Hinge JointFound in your elbowAllows you to move arm forward and backwardLike a hinge in a door

Gliding JointAllows bones to glide over one anotherLike small bones in your feet-allows flexing when walking

Pivot JointTop 2 vertebrae in your neck. Allows you to move your head side to side.

Ball and Socket JointFound in your shoulder or hipAllows you to move up/down, forward/backward, or rotate in a circle

Saddle JointAt the base of your thumbAllows you to rotate your thumb and grasp objects with your hand

Possible injuries and illnessesRheumatoid Arthritis-immune system attacks body tissues. Joints become inflamed, swollen, stiff, and deformedOsteoarthritis- degenerative joint disease where cartilage covering the bones become thin and rough.Sprain (ligament)- could either overstretch or possibly tearStrain (tendon)- could either overstretch or possibly tear

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